Barley yield and malt characteristics as affected by nitrogen and final irrigation timing

Idaho is a major malt barley (Hordeum vulgare L.) producer in the United States. Production is concentrated in the semi-arid Snake River Plain region of southern Idaho. Irrigation and fertilizer N applications are two of the most important managed factors. Research was conducted at the University of Idaho Kimberly Research & Extension Center near Kimberly, ID, to determine yield, grain quality, and malt characteristics as affected by N application rate (0, 56, 112, and 168 kg N ha(-1) and final irrigation timing at Feekes 10.0 (boot; F10.0), Feekes 11.2 (soft dough; F11.2), and +7 d after Feekes 11.2 (+7F11.2). Irrigation termination at F10.0 resulted in decreased yields and unacceptable malt characteristics across N rates. Irrigation termination at F11.2 and +7F11.2 yielded 6,439 kg ha(-1) at a fertilizer N application of 56 kg N ha(-1), similar to higher N applications. Greater predicted yields up to 6,886 kg ha(-1) were calculated by regression analysis with applications up to 147 kg N ha(-1). Grain yield, protein, plumps, and test weights did not differ at any N rate for F11.2 or +7F11.2. Malt extract, free amino N, and diastatic power were similar for the F11.2 and +7F11.2 irrigations. Malt beta-glucan content did not differ up to 56 kg N ha(-1) for any treatment, but reductions of up to 30 mg kg(-1) were measured at higher N rates for the +7F11.2 irrigation. Results warrant further investigations into increased N applications and provide evidence of the effects of irrigation cutoff timing and N for malt barley.